The present invention relates generally to automotive electronics and in particular to a method of simplifying control wiring within the engine compartment by mounting control electronics on the air intake manifold.
Internal combustions used in automobiles and the like employ sophisticated engine control technologies making use of a variety of sensors and actuators and communication with microprocessor-based control circuitry. Generally engine control provided by these systems offers increased performance, reduced emissions and higher reliability in the operation of the vehicle.
Currently, the microprocessor-based control circuitry may be located near the vehicle firewall to provide a secure mounting of the circuitry away from the high temperature components of the engine and communicating with driver instrumentation in the passenger compartment.
The control circuitry communicates with a variety of sensors on or close to the engine including, for example, sensors for air mass flow, engine temperature, throttle position, engine speed and crankshaft position. The control circuitry in receiving these sensor signals, produces actuator signals to control throttle valves, fuel injectors, ignition coils, engine valves and the like.
The sensors and actuators must be connected to the control circuitry by wiring and the wiring must be of sufficient gauge to resist breaking under the tensile load and flexures incident to the normal service. The wires are therefore typically bound together in xe2x80x9charnessesxe2x80x9d to improve their mechanical resilience and may be sheathed to better resist abrasion.
Wiring harnesses represent a significant cost in manufacturing of the vehicle, not only in cost of material and manufacture, but also in costs of routing and connection to the sensors and actuators. Mechanically robust harnesses add weight to the vehicle affecting vehicle mileage and emissions. The harness with its attendant branching wire sets can increase the clutter in the engine compartment adversely affecting the assembly, maintenance and repair of the engine. Further, long wire harnesses are a source of Electromagnetic Interference (EMI) which may adversely affect the performance of all vehicle electronics.
The present inventors have recognized that a significant number of actuators are concentrated near the heads of the engine cylinders. Accordingly, placement of the control electronics at a central location between the engine cylinders can significantly reduce wiring. The sensitivity of the electronics to high temperatures normally occurring near the engine may be solved by a special circuit carrier supported by the intake manifold that may block the transmission of heat to the circuitry from the engine and may remove heat internally generated by such circuitry.
Specifically, the present invention provides an intake manifold circuit carrier including an air intake manifold providing chamber walls conducting air from a throttle body opening to a plurality of exit ports associated with locations of cylinders on an internal combustion engine. Support walls are provided extending outwardly from the chamber walls to define a volume adjacent to the chamber walls. The circuit board having circuit components mounted thereon and including a first aperture is attached to a heat conductive plate on the first side of the circuit board, the heat conductive plate being in thermal communication with it to form a laminated plate assembly. The heat conductive plate has a second aperture aligned with the first aperture in the circuit board and the laminated plate assembly is attached to an upper edge of the support walls to cover the volume with the circuit board internal to the heat conductive plate with respect to the volume.
Thus, it is one object of the invention to create a hospitable environment for temperature sensitive electronic components near the actuators associated with engine cylinders.
A throttle body may be included having a central lumen and attached to the laminated plate assembly with the lumen aligned with the first and second apertures so as to place the throttle body in thermal communication with the heat conductive plate. The throttle body may include fins projected inward to the lumen to conduct heat from the throttle body to air passing across the fins.
Thus it is another object of the invention to provide a path of heat conduction away from the electronics into the air normally aspirated by the engine.
The support walls may be molded of heat conductive plastic or may be an integral part of the intake manifold.
Thus it is another object of the invention to provide a path of heat conduction into the air normally drawn through the chamber walls of the intake manifold.
The short harnesses required between the circuit card and the actuators on the cylinder heads may be conventional wire harnesses terminating in electrical connectors that may connect to the actuators or may be extensions of a flexible circuit board substrate of the circuit board terminating in electrical connectors or may be a conductor assembly (for example, a rigid plastic) having electrical connectors attached to corresponding connectors on the printed circuit board and also attached to the control component or may be conductors attached directly to the air intake manifold.
Thus it is another object of the invention to provide great flexibility in the construction of the harnesses based on their short length and close proximity to the control actuators.
In an alternative embodiment of the invention, the intake manifold circuit carrier may include an air intake manifold providing chamber walls conducting air from an entrance port to a plurality of exit ports associated with locations of the cylinders on an internal combustion engine. Support walls may extend outward from the chamber walls to define a volume adjacent to the chamber walls. A circuit board having circuit components mounted thereon may be sandwiched between the upper edge of the support walls and a cover shroud attachable at the upper edge of the support walls, the cover shroud when so assembled, providing air channels conducting air from a throttle body port in the cover shroud pass the circuit board leading to the entrance port of the air intake manifold.
Thus it is another object of the invention to provide direct airflow of aspirated engine air across the circuit board to provide cooling thereof.
The foregoing and other objects and advantages of the invention will appear from the following description. In this description, reference is made to the accompanying drawings, which form a part hereof, and in which there is shown by way of illustration, a preferred embodiment of the invention. Such embodiment and its particular objects and advantages do not define the scope of the invention, however, and reference must be made therefore to the claims for interpreting the scope of the invention.